Method of preparing lubricating



Patented Apr. 2, 1946 A UNITED STATES PATENT. OFFICE 2,397,662 1 i r v METHOD OF ranias n uc LUBRICATING Lawrence M. Henderson, Winnetka', and Weldon Grant Annable, Mundelein, Ill., .assignorsjto The Pure Oil Company, Chicago, 111., a corporation of Ohio No Drawing. Application July 2, 1943,

Serial'No. 493,300 p Q 196-50) 7 This invention relates to a method for prepar-' for this is that in batch operation it is usually ing lubricating oils of lower viscosity from lubrinecessary to leave a residuum in the still of about eating oil stock of higher viscosity and is. more 10 to 12%"0f the charge, whereas insemi-conparticularly concerned with a method of prepartinuous or continuous operation the residuum can ing neutrals from cylinder stock. be reduced to l .to 6% or less of the total oil It has already been proposed to prepare neucharged to the process. Where continuous or .tral from bright stock by subjecting the latter semi-continuous distillation is practical the oil to light cracking distillation. Wagner et a1. Patmay be heated in a pipe still and then passed to may use stocks obtained from Pennsylvania grade oils or from Mid-Continent oils. The light crackent #2,155,745 describes a process which has been an enlarged distillation zone containing a bod 0 used commercially. Our invention is directed to oil under o g i illation. V e an improved method of preparing neutrals from In th preferred method of carrying out our residual tocks, I c invention we maintain the temperature of the It is common practice to add to lubricating oils cylinder stock undergoingcracking distillation in pour depressants for the purpose of lowering-th the neighborhood of approximately 700 F. and pour point of the oil, Th pour depressant which 15 inject into the cylinder stock an amount of live' is most widel used is that known as Paraflow. steam approx m ly equivalent to the amount One of the difliculties experienced with oils conof oil vapors taken overhead from the still. We taining pour depressants is that the product is have found thatif the distillation of cylindernot always pour stable, that is, some oils when stock is properly conducted, yields of distillatein subjected to temperature variations from 20 excess of 90% can be obtained. The distillation F. or lower to about 65 F. congeal at temperais preferably conducted at such a ratewand at tures considerably above the A. S. T. M, pour such temperature that the viscosity of the overpoint of the oil. Our invention overcomes the head stream is maintained at appr x 100 difficulty which issometimes encountered with Saybolt at 100 F, oils as heretofore made and makes possible the In the distillation of the cylinder stock it is preparation of neutrals from cylinder stock which advantageous to add a small amount of low boilneutrals ive pour stable blended oils when pour ins ydrocarbon, such as kerosene, to assist in the depressants are added thereto. 7 distillation.

An object of our invention is to prepare less The overheadstock from the light c ack n d viscous lubricating oils from more viscous lubri- 3 tillation of thecylinder stock will have a high eating oil stock. I v v pour point due to the presence of crystalline or Another object of our invention is to prepare semi-crystalline wax in the oil. The presence of neutral lubricating oil stock from cylinder stock. this wax interferes with conventional centrifugal Another object of our invention is to prepare or-filter press dewaxing of the stock. We have neutral oils from cylinder stock, which neutrals discovered, however,:that if a small amount of are pour stable when small amounts of pourdepetrolatum, obtained b conventional cold cenp such as Parafiow, are added thereto. trifugal dewaxing of naphtha-cylinder stock solu A still furt r object of o invention is o p tions, is added to the overhead stock, the stock vide a method for producing a h yield of neu-i is readily amenable to centrifugal dewaxing In tr 0 o P ro I accordance with our'invention, therefore, ,we

ther Objects Of Our iinventiol} W111 become added to the overhead tock approximately 5 to manifest from the following description. 20% of petrolatum preferably in the fo of a a In accordance with our nven y d naphtha solution, after which the stock is substock is subjected to a light cracking distillatio jected. to centrifugal dewaxing in the presence of in a batch semi-continuousor continuous still. naphtha in the conventional manner As cylinder stocks suitable for our invention we I Before dilution of the Stock with naphtha for centrifuging, it may be desirable to remove from ing distillation of cylinder stock is carried out at the overhead stock low 'bmhng hydrocarbons within the gasoline,'kerosene and gas oil range. iifigiiifu ist'hiifi $355221; 555523325313 In the ee ee n my be i d 650 to 800 F. in the manner set forth in the a'ytemperfiture of approxlmately aforesaid Wagner et a1. patent in connection with h hlfher meltmg Waxes are removed and an the cracking distillation of bright stock. Al- 011 havmg P0111 P011115 of approxlmately though the distillation may be carried out in a y be otftained- S at l s pre bly batch still, we preferred to carr out the crackblended the P r p portwns. oibright ing distillation in a semi-continuous or contin stock and neutrals to the desired viscosit and uous distillation operation for the reason-that will be f und to respond to Parafiow and other higher yields of overhead or neutral stock can be pour depressants, so that the pour of the blend obtained than in batch'distlllation; The reason can be reduced to approximately 30 F. b adat j dition of 1% of Paraflow, and the pour point of the oil will remain stable.

If desired,the' overhead stock made by the light cracking distillation after addition of the petrola- 62.1 A. P. I. gravity naphtha and chilled non shock from 100 F. to -35 F. The chilled solutions were then centrifuged and the resulting oil and wax cake examined after separating the tum and centrifugal dewaxing may be blended '5 naphtha from each. The following table gives the with pressed distillate and subjected todistillaresults obtained from the examination of the tion to reduce to desired viscosity in the manner products of the dewaxing operation:

set forth in Wagner et al. Patent #1155345. g Table IV As an example of the invention, cylinder stock u from a Pennsylvania oil having the following 1 characteristics: gfi ggggg p e it A P I gravity 250 mm petmlatum ittofi'vi ea tyagtia @ZIIIIIIIIIIIIII: 123- ittttfitfiifit i.rlrirrri m 545 38%:ifffiti ififi l thti fitfii i*,- 4*. Fire 1 a 7 r 600 vnlaphtha 1u o n 17.5 43.4 was subjected to a light cracking distillationin'a a '78.? 1 :6 semicontinuous operation at a temperature of ififfiigifittflj'i 2 53i '23,"; 690 120710 F. superheated steam at a'tempera- Pour, i 25 ture-of 550 F. was injectedinto the cylinder-stock I in a-ratio of one part by weight of steam to one 7 part by weight of'oil vaportaken overhead. The f??? cylinder stock was mixed with kerosene prior to percent of 621 naphth 1 distillation. The following table gives the quan- 25 gi g' gg g' g a'ggaggrgggggrgg. tity of materials charged and the yield obtained fi --'----r---- i137. 1-. based on-the cylinder stock-charged: 533s? $13 M. P., F 120' 2s Table I Appearance Cub-i0 cenfl Percent based 2?? g meters it??? fi rt fiiui. r r The wax obtained from the operation on' the ggf 'gg overhead stock to which petrolatum stock had not Kerosene recovered; 1: 000 :::::::::I 35 been'a'dded wasp r ly crystalline and couldlnnt ggg g gg be continuously discharged from a super centrie Loss- -::II::::::::::: '300 0:8 fuse, wh s th wa t in d fr m th sa p I to which the petrolatuni stock hadtbeen' added. The cracked overhead was divided and each of 40 amrphus;and the Stock be Satlsfac' two 5-gallon samples was subjected to iconven- 9 1 dewaxed'm Moreover, tional naphtha cold centrifugal dewaxing in a m splte'of the ofphe 15% m super centrifuge. To onesample 15% of petroto one i the yleld of x I than latum was added prior to centrifuging. 4 The charthat obtamed from the sample lt t acteristics of the samples before and after addil eie had t been q thereby g n petrolatum were as follows: r r mg that in the latter operation agood separation of 011 and Wax had not been obtained. Moreover, J Table II theyield of dewaxed lubricating oil from the blend I containing petrolatum was increased by approxi Sample samplp'after mately the percent of petrolatum added; .This. is gf g fgg gf gggz gg g a decided advantage since .petrolatum islworth I v I considerably less than the lubricating oil. v a -A 10W S. A. E. lubricating oil-was made by ggfidg i gg ggrgg'fl fbi; blending together the .dewaxed oil to-which ,petroifg 93;

latum has been added before dewaxing, Pennsylm F I I 1 5 135 Vania bright stock and Pennsylvania neutrals in thefollowing proportions: M 1 1 Before dewaxing, both samples were subjected Parts by Volume to distillation with 300? F. steam in order to re- DeWaXed cracked stock 77 move light ends which might interfere with the Brllght stockc 110 blending and dewaxing with naphtha. The char- Neutrals acteristics of the two samples after removal 'of'the The characteristics of t g t stock and light end We e as fo l w neutrals used in the blend wereas follows: 7 u

' Table III Table v s 1 with Bri'htstock Neutrals tartar g a 7 A. P. I. gravity i....' 26.0 35, 0 Pour, FY +15 +30 .29 3 29,9 Sayboltviscosity at 100 F v V Saybolt viscosity at 210 F lre, 465 440 Percent residue remaining To the blend'was added 1% by volume-of Para-' f flow and the resulting productwas testedt for pour Each of the stocks, after removal of the light point and for slow and rapid'cycle fpour stability. ends, was blended with three "parts by volume of slew cycle pour stability lis determined by ing to the mark pour jars used in making pour point determinations under A. S. T. M. designation (D-97-39) with oil samples at room temperature. The samples are placed in a l-gallon capacity Thermos jug. In one sample is inserted a short thermometer through the cork stopper in the pour jar so that the top of the mercury bulb is /8 inch below the surface of the oil in the jar. The other samples in the jug are stoppered only. The pour jars should be placed in the jug in a single row around the inside wall. The jug is then tightly covered and placed in a refrigerator maintained at -40 F. for a sufllciently long time (preferably overnight) to cool the oil samples down to 25 F.

After the samples have cooled to 25 F. or

lower, the jug is removed from the refrigerator,

the samples are removed from the jug and permitted to warm up to 65 F. (plus or minus 5 F.) without applying heat. The Thermos jug should be covered as soon as the oil samples are removed so that the inside of the jug remains reasonably cool. It will take the oil samples approximately 1 hour to warm up from 25 F. to +65 F. by standing in a room at a temperature of approximately 75 F. The samples should be preferably separated during the warming-up period and upon attaining a temperature of approximately 65 F. should be clear and not hazy.

As soon as all the samples have warmed up to approximately 65 F. they are returned to the Thermos jug; the Thermos jug is covered and allowed to remain in the laboratory atmosphere for 2 hours. The temperature of the oil samples is dropped from approximately 65 F. to approximately 40 F. in the two hours during which the jug is left standing in the room. Thereupon the jug is placed in a refrigerator maintained at -10 F. and the condition of the oil is observed hourly from the time the temperature reached +25 F. until a temperature of F. is reached. Cooling will occur at the rate of 5 to 7 F. per hour during the time the temperature of the samples dropped from +30 to +20 F. If any samples become solid before the temperature of +20 F. is reached they are removed from the jug and the temperature recorded at which the sample became solid. When the temperature of +20 F. is reached, the jug is removed from the refrigerator and placed in a second refrigerator maintained at 40 F. and the temperature and condition of the oil observed hourly. Care should be exercised not to disturb the oil more than is absolutely necessary when making hourly observation.

In extremely warm weather it may be necessary to make observations every hour and a half instead of every hour in order to maintain the desired cooling rate of the samples. The test need not be taken below F. on the second cycle and oils remaining fluid down to the A. S. T. M.

The pour bath is cooled as rapidly as possible to -40 F. When the oil samples reach 25 F. they are removed from the pour bath and are permitted to warm up to 65 F. (plus or minus 5 F.) as in the slow cycle test. After the samples warm up to the 65 F. temperature they are returned to the pour bath which is now maintained at approximately -30 F. The samples are allowed to cool down to +20 F. and the pour bath is then rapidly cooled to 40 or F. The condition of the oil samples is observed at 20 F. for oils with a pour point of 25 F. or lower, and at a temperature of 10 above the pour point of the oil for oils having a pour point above 25 F. The condition of the oil is recorded as fluid or solid at the temperature of observation. Oils which remain fluid under these conditions are considered to be satisfactory as far as this test is concerned. In" testing the oil to determine whether it is fluid or solid, the A. S.'T. M. pour procedure is used; that is, the jar is held in a horizontal position for not more than 5 seconds. The pour test and pour stability results on the blend are given in Table VI:

Table VI Pour stability Slow cycle:

Fluid at 15 F; Solid at --20 F.

20" F. Rapid c cle at 10 F. Fluid.

' is pour stable in the presence of small amounts pour point of the sample are considered satisfactory from the standpoint of this test but such samples must still pass the rapid cycle test.

In making the rapid cycle pour stability test, the pour jars are filled to the mark with the oil samples at room temperature. Thermometers are inserted as in the A. S. T. M. pour test and a heavy cardboard gasket having an outside diameter 1 /2 inches larger than the outside diameter of the pour jars is snugly fitted on the outside of the pour jars and rests on the top of the jacket surrounding the pour jar, so that the gasket closes the space between the pour jar and the Jacket.

of Paraflow or other pour depressants. By crack ing cylinder stock instead of bright stock a higher yield of finished product can be obtained at lower cost than can be obtained by cracking bright stock, due to the fact that in our process the steps of percolation of cylinder stock through clay and cold centrifuging of the stock to remove wax are avoided. The percolation step involves unnecessary loss of desirable material.

We claim:

The method of preparing lubricating oil which comprises distilling cylinder stock fromPennsylvania oil under light cracking conditions at a temperature of approximately 700 F. at pressures not substantially above atmospheric pressures in the presence of a light hydrocarbon diluent, injecting steam into the body of cylinder stock undergoing distillation at such rate that the volume of steam is approximately equal to the volume of hydrocarbon vapors produced, condensing the vapors, continuing the distillation until approximately 91.2% by volume of the cylinder stock is distilled, adding to the distillate approximately 15% of petrolatum, removing from the mixture fractions boiling within and below the gas oil range, diluting the remainder with naphtha, chilling the solution to a temperature of approximately 35 F., centrifuging it to remove wax and removing the naphtha from the dewaxed oil.

LAWRENCE M. HENDERSON. WELDON GRANT ANNABLE. 

